Control plane location solution to support wireless access

ABSTRACT

Techniques for supporting a control plane solution for location services and positioning are described. In an aspect, an Evolved Serving Mobile Location Center (E-SMLC) may communicate with a Mobility Management Entity (MME) to support location services and positioning for a UE. In one design, the E-SMLC may receive a location request from the MME, perform a positioning procedure with the UE in response to the location request, and send a location response to the MME after completing the positioning procedure. For a UE-assisted or UE-based positioning procedure, the E-SMLC may send a downlink positioning message to the UE via the MME and may receive an uplink positioning message from the UE via the MME. For a network-based positioning procedure, the E-SMLC may send a network positioning request message to an eNB via the MME and may receive a network positioning response message from the eNB via the MME.

This application is a Continuation application of U.S. patentapplication Ser. No. 12/541,841, filed Aug. 14, 2009, titled “ControlPlane Location Solution to Support Wireless Access”, which claimspriority to Provisional U.S. Application Ser. No. 61/089,795, filed Aug.18, 2008, and Provisional U.S. Application Ser. No. 61/142,556, filedJan. 5, 2009, each being titled “Control Plane Location Solution toSupport LTE Wireless Access,” assigned to the assignee hereof, andexpressly incorporated herein for all purposes by reference.

BACKGROUND

I. Field

The present disclosure relates generally to communication, and morespecifically to techniques for supporting location services (LCS) foruser equipments (UEs).

II. Background

It is often desirable, and sometimes necessary, to know the location ofa UE, e.g., a cellular phone. The terms “location” and “position” aresynonymous and are used interchangeably herein. For example, an LCSclient may desire to know the location of the UE and may communicatewith a location center in order to request the location of the UE. Thelocation center and the UE may then exchange messages, as necessary, toobtain a location estimate for the UE. The location center may thenreturn the location estimate to the LCS client.

A wireless network may support location services and positioning.Positioning refers to a functionality that determines a geographicallocation of a target UE. Location services refer to any services basedon or related to location information, which may include any informationrelated to the location of a UE, e.g., measurements, a locationestimate, etc.

The wireless network may implement a control plane solution or a userplane solution to support location services and positioning. In acontrol plane solution, messages supporting location services andpositioning may be carried as part of signaling transferred betweenvarious network entities, typically with network-specific protocols,interfaces, and signaling messages. In a user plane solution, messagessupporting location services and positioning may be carried as part ofdata transferred between various network entities, typically withstandard data protocols such as Transmission Control Protocol (TCP) andInternet Protocol (IP). A control plane solution may be preferred sinceit may enable network-based positioning, which may not be supported by auser plane solution. Furthermore, a control plane solution may be morecompatible with existing solutions, may be usable with any UE, and maybe more reliable and/or more accurate.

SUMMARY

Techniques for supporting a control plane solution for location servicesand positioning are described herein. In an aspect, an Evolved ServingMobile Location Center (E-SMLC) may communicate with a MobilityManagement Entity (MME) to support location services and positioning fora UE. In one design, the E-SMLC may receive a location request from theMME and may perform a positioning procedure with the UE in response tothe location request. The E-SMLC may send a location response to the MMEafter completing the positioning procedure.

In one design, for a UE-assisted or UE-based positioning procedure, theE-SMLC may send a downlink positioning message to the MME for forwardingto the UE. The E-SMLC may thereafter receive an uplink positioningmessage sent by the UE and forwarded by the MME. The downlinkpositioning message may request location information (e.g.,measurements, a location estimate, etc.) from the UE and may includeassistance data for the UE, a request for UE capabilities, etc. Theuplink positioning message may include the requested locationinformation. The downlink and uplink positioning messages may beencapsulated in other messages at lower layer.

In another design, for a network-based positioning procedure, the E-SMLCmay send a network positioning request message to the MME for forwardingto an evolved Node B (eNB). The E-SMLC may thereafter receive a networkpositioning response message sent by the eNB and forwarded by the MME.The network positioning request message may request location informationfrom the eNB, and the network positioning response message may includethe requested location information. The network positioning request andresponse messages may be encapsulated in other messages at lower layer.

Various aspects and features of the disclosure are described in furtherdetail below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1, 2 and 3 show block diagrams of three network architectures.

FIGS. 4A and 4B show exemplary protocol stacks at various networkentities.

FIG. 5 shows a call flow for a Mobile Terminated Location Requestprocedure.

FIG. 6 shows a call flow for a Mobile Originated Location Requestprocedure.

FIG. 7 shows a call flow for an emergency call.

FIG. 8 shows a call flow for a UE-assisted or UE-based positioningprocedure.

FIG. 9 shows a call flow for a network-based positioning procedure.

FIGS. 10, 11 and 12 show processes for supporting location services andpositioning by an E-SMLC, an MME, and a UE, respectively.

FIG. 13 shows a block diagram of various network entities.

DETAILED DESCRIPTION

The control plane solution described herein may be used for variouswireless networks, which may implement various radio technologies. Forexample, the control plane solution may be used for a Long TermEvolution (LTE) network that may implement Evolved Universal TerrestrialRadio Access (E-UTRA). LTE is part of 3GPP Evolved Packet System (EPS).LTE, E-UTRA and EPS are described in documents from an organizationnamed “3rd Generation Partnership Project” (3GPP). The control planesolution may also be used for other wireless networks and other radiotechnologies.

The control plane solution described herein may also be supported withvarious network architectures. Each network architecture may beassociated with a set of network entities that may be coupled in aspecific manner and may communicate via specific interfaces to providevarious services. Some exemplary network architectures are describedbelow.

FIG. 1 shows a block diagram of a first network architecture 100, whichmay be suitable for an LTE network. A UE 110 may communicate with an eNB120 in a radio access network (RAN) to obtain communication services.The RAN may include other network entities not shown in FIG. 1 forsimplicity and may also be referred to as an Evolved UniversalTerrestrial Radio Access Network (E-UTRAN). eNB 120 may also be referredto as a Node B, a base station, an access point, etc. UE 110 may also bereferred to as a mobile station, a terminal, an access terminal, asubscriber unit, a station, etc. UE 110 may be a cellular phone, apersonal digital assistant (PDA), a wireless device, a wireless modem, awireless router, a laptop computer, a telemetry device, a trackingdevice, etc.

UE 110 may also receive and measure signals from one or more satellites190 and obtain pseudo-range measurements for the satellites. Satellites190 may be part of a Global Navigation Satellite System (GNSS), whichmay be the United States Global Positioning System (GPS), the EuropeanGalileo system, the Russian GLONASS system, or some other GNSS. UE 110may also measure signals from eNBs and obtain timing measurements (e.g.,for time of arrival (TOA) or observed time difference of arrival(OTDOA)), signal strength measurements, and/or signal qualitymeasurements for the eNBs. The pseudo-range measurements, timingmeasurements, signal strength measurements, and/or signal qualitymeasurements may be used to derive a location estimate for UE 110. Alocation estimate may also be referred to as a position estimate, aposition fix, etc.

eNB 120 may communicate with an MME 130, which may perform variouscontrol functions such as mobility management, gateway selection,authentication, bearer management, etc. MME 130 may communicate with anE-SMLC 140, a Home Subscriber Server (HSS) 150, and a Gateway MobileLocation Center (GMLC) 160. E-SMLC 140 may support UE-based,UE-assisted, network-based and/or network-assisted positioning methodsand may support one or more MMEs. E-SMLC 140 may also be referred to asa location server (LS), a standalone SMLC (SAS), etc. E-SMLC 140 mayalso communicate with GMLC 160 to support location services. GMLC 160may perform various functions to support location services, interfacewith external LCS clients (e.g., an LCS client 170), and provideservices such as subscriber privacy, authorization, authentication,billing, etc. GMLC 160 may include a Home GMLC (H-GMLC), a Visited GMLC(V-GMLC), and/or a Requesting GMLC (R-GMLC). A Location Routing Function(LRF) 162 may communicate with GMLC 160 and may route or help routeIP-based emergency calls to a Public Safety Answering Point (PSAP)associated with the calling UE's location. HSS 150 may also communicatewith GMLC 160. HSS 150 may store subscription information for users,perform authentication and authorization of users, and provideinformation about user location and routing information when requested.

A Serving Gateway (S-GW) 180 may perform various functions related to IPdata transfer for UEs such as data routing and forwarding, mobilityanchoring, etc. A Packet Data Network (PDN) Gateway 182 may performvarious functions such as maintenance of data connectivity for UEs, IPaddress allocation, etc. An IP Multimedia Subsystem (IMS) network 184may include various network entities that may support IMS services suchas Voice-over-IP (VoIP) calls. A data network 186 may include publicnetwork, such as the Internet, and/or private network. A PSAP 188 may beresponsible for answering emergency calls (e.g., for police, fire, andmedical services) and may communicate with IMS network 184, LRF 162and/or other network entities directly or indirectly. The variousnetwork entities in FIG. 1 may be part of a Home Public Land MobileNetwork (H-PLMN) or a Visited PLMN (V-PLMN).

FIG. 1 also shows the interfaces between various network entities. Thefollowing interfaces may be defined or enhanced to support control planesolution in LTE:

SLs interface between MME 130 and E-SMLC 140,

SLg interface between MME 130 and GMLC 160, and

Lh interface between HSS 150 and GMLC 160.

The Lh interface between HSS 150 and GMLC 160 may be an enhanced versionof an Lh interface between a GMLC and an HLR/HSS in Wideband CodeDivision Multiple Access (WCDMA) and Global System for MobileCommunications (GSM). The Lh interface may enable HSS 150 to provide theMME address, the VPLMN identity, and/or other information to GMLC 160.The SLg interface may be similar to an Lg interface between a GMLC andeither a Serving GPRS Support Node (SGSN) or a Mobile Switching Center(MSC). The SLg interface may enable an H-GMLC to provide the MME addressto a V-GMLC when the location of a particular UE is being requested bythe H-GMLC. Furthermore, to support control plane solution in LTE, anS1-MME interface between eNB 120 and MME 130 may be modified throughaddition of new messages and parameters. An LTE-Uu interface between UE110 and eNB 120 may also be modified at an upper level through use of anew or modified positioning protocol.

FIG. 1 shows a specific design of the first network architecture, withE-SMLC 140 being connected to MME 130. The connection between E-SMLC 140and MME 130 may avoid the need to stop and restart a location sessionfor UE 110 for an inter-eNB but intra-MME handover. Other variations ofthe first network architecture are also possible. For example, E-SMLC140 and MME 130 may be combined. More efficient signaling between E-SMLC140 and eNB 120 may also be supported to bypass MME 130.

FIG. 2 shows a block diagram of a second network architecture 102, whichmay also be suitable for an LTE network. In second network architecture102, MME 130 may communicate with E-SMLC 140, HSS 150, and GMLC 160.E-SMLC 140 and HSS 150 may also communicate with GMLC 160. The networkentities in FIG. 2 may perform the functions described above for FIG. 1.

FIG. 2 also shows the interfaces between various network entities. Thefollowing interfaces may be defined or enhanced to support control planesolution in LTE:

SLs interface between MME 130 and E-SMLC 140,

SLg interface between E-SMLC 140 and GMLC 160,

SLg* interface between MME 130 and GMLC 160, and

Lh interface between HSS 150 and GMLC 160.

The SLg* interface may be similar to the Lg interface between a GMLC andeither an SGSN or an MSC and may be avoided if the Lh interface issupported. The SLg and SLg* interfaces may be avoided if E-SMLC 140 andGMLC 160 are logically combined. The S1-MME interface and the LTE-Uuinterface may be modified to support the control plane solution.

FIG. 2 shows a specific design of the second network architecture, withE-SMLC 140 being connected to MME 130 and GMLC 160. The connectionbetween E-SMLC 140 and GMLC 160 may avoid the need to stop and restart alocation session for UE 110 for both an inter-eNB handover and aninter-MME relocation. Other variations of the second networkarchitecture are also possible. For example, E-SMLC 140 and GMLC 160 maybe combined, E-SMLC 140 and MME 130 may be combined, etc. More efficientsignaling between E-SMLC 140 and eNB 120 may be supported to bypass MME130.

FIG. 3 shows a block diagram of a third network architecture 104, whichmay also be suitable for an LTE network. In third network architecture104, E-SMLC 140 may communicate with eNB 120. MME 130 may communicatewith HSS 150 and GMLC 160. HSS 150 may also communicate with GMLC 160.The network entities in FIG. 3 may perform the functions described abovefor FIG. 1.

FIG. 3 also shows the interfaces between various network entities. Thefollowing interfaces may be defined or enhanced to support control planesolution in LTE:

LTE-Iupc interface between eNB 120 and E-SMLC 140,

SLg interface between MME 130 and GMLC 160, and

Lh interface between HSS 150 and GMLC 160.

The LTE-Iupc interface may be similar to an Iupc interface between aRadio Network Controller (RNC) and a SAS in WCDMA.

FIG. 3 shows a specific design of the third network architecture, withE-SMLC 140 being connected to eNB 120. The connection between E-SMLC 140and eNB 120 may allow for use of enhanced RRC-based positioning. Othervariations of the third network architecture are also possible.

FIGS. 1, 2 and 3 show three exemplary network architectures that cansupport location services and positioning. Other network architecturesmay also be used to support location services and positioning and mayinclude network entities that may be coupled in other manners. Thesevarious network architectures may also include network entities notshown in FIGS. 1 to 3. The network entities in FIGS. 1 to 3 may also bereferred to by other names. For example, E-SMLC 140 may be referred toas, and/or may include the functionality of, a location center, apositioning center, Position Determination Entity (PDE), etc.

Various call flows may be defined to support location services andpositioning. Each call flow may include a sequence of messages exchangedbetween various network entities. As shown in FIGS. 1 to 3, differentnetwork architectures may support communication between differentnetwork entities. For example, E-SMLC 140 may be able to communicatewith only MME 130 in FIG. 1, with both MME 130 and GMLC 160 in FIG. 2,and with only eNB 120 in FIG. 3. The call flows may thus be dependent onthe selected network architecture, which may support communicationbetween certain network entities. For clarity, much of the descriptionbelow is for the first network architecture shown in FIG. 1, with E-SMLC140 being able to communicate directly with MME 140 but not eNB 120 orGMLC 160.

FIG. 4A shows exemplary protocol stacks at UE 110, eNB 120, MME 130 andE-SMLC 140 for communication between UE 110 and E-SMLC 140 based on thefirst network architecture in FIG. 1. UE 110 may communicate with E-SMLC140 using an LTE Positioning Protocol (LPP). At UE 110, LPP may operateover Radio Resource Control (RRC), Packet Data Convergence Protocol(PDCP), Radio Link Control (RLC), and Medium Access Control (MAC) inLayer 2 (L2), and E-UTRA airlink in Layer 1 (L1). eNB 120 maycommunicate with UE 110 via RRC, PDCP, RLC, MAC and L1. eNB 120 may alsocommunicate with MME 130 via S1 Application Protocol (S1-AP), StreamControl Transmission Protocol (SCTP), IP, L2 and L1. MME 130 maycommunicate with E-SMLC 140 via LCS Application Protocol (LCS-AP), SCTP,IP, L2 and L1. LCS-AP may be functionally similar to parts of BaseStation System Application Part-Location Services Extension (BSSAP-LE),Base Station System Location Services Assistance Protocol (BSSLAP), orRadio Access Network Application Part (RANAP) in 3GPP.

UE 110 may exchange (e.g., send and/or receive) LPP messages with E-SMLC140. The LPP messages may be encapsulated in RRC messages forcommunication between UE 110 and eNB 120, encapsulated in Non-AccessStratum (NAS) transport messages for communication between eNB 120 andMME 130, and encapsulated in LCS-AP messages for communication betweenMME and E-SMLC 140. The RRC messages may be exchanged between UE 110 andeNB 120 with the protocols shown for these entities in FIG. 4A. The NAStransport messages may be exchanged between eNB 120 and MME 130 with theprotocols shown for these entities in FIG. 4A. The LCS-AP messages maybe exchanged between MME 130 and E-SMLC 140 with the protocols shown forthese entities in FIG. 4A.

FIG. 4B shows exemplary protocol stacks at eNB 120, MME 130 and E-SMLC140 for communication between eNB 120 and E-SMLC 140 based on the firstnetwork architecture in FIG. 1. eNB 120 may communicate with E-SMLC 140via an LPP annex (LPPa) protocol, which may be a thin protocol similarto LPP used between UE 110 and E-SMLC 140. LPPa may reside on top ofS1-AP, SCTP, IP, L2 and L1 between eNB 120 and MME 130 and on top ofLCS-AP, SCTP, IP, L2 and L1 between MME 130 and E-SMLC 140.

FIG. 4A shows the protocol stacks for communication between UE 110 andE-SMLC 140. FIG. 4B shows the protocol stacks for communication betweeneNB 120 and E-SMLC 140. Communication between other network entities mayalso be supported by a suitable set of protocol stacks. For example, UE110 may communicate with MME 130 via NAS. NAS may reside on top of RRC,PDCP, RLC, MAC and L1 between UE 110 and eNB 120, and on top of S1-AP,SCTP, IP, L2 and L1 between eNB 120 and MME 130. Other protocol stacksmay also be used for communication between the various network entitiesfor each of the three network architectures described above. LPP may beused end to end (e.g., between UE 110 and E-SMLC 140) for all threenetwork architectures described above.

For LTE, MAC is described in 3GPP TS 36.321, RLC is described in 3GPP TS36.322, PDCP is described in 3GPP TS 36.323, RRC is described in 3GPP TS36.331, and S1-AP is described in 3GPP TS 36.413. SCTP is described inRFC 2960, and IP is described in RFCs 791 and 2460. These various 3GPPTS documents are publicly available from 3GPP, and these various RFCsare publicly available from The Internet Engineering Task Force (IETF).

FIG. 5 shows a design of a call flow 500 for a Mobile TerminatedLocation Request (MT-LR) procedure for the first network architectureshown in FIG. 1. LCS client 170 may initiate a common MT-LR procedure inpacket-switched (PS) and circuit-switched (CS) domain with GMLC 160 andHSS 150 in order to send an LCS service request (step 1). A locationprocedure 510 may be performed in response to the LCS service request.

For location procedure 510, GMLC 160 may send a Provide SubscriberLocation (PSL) message to MME 130, which may be indicated by HSS 150(step 2). The PSL message may include the type of location informationbeing requested (e.g., current location, velocity, etc.), anInternational Mobile Subscriber Identity (IMSI) of the UE subscriber,LCS quality-of-service (QoS) information (e.g., accuracy, response time,etc.), privacy related action for the UE subscriber, etc. If GMLC 160 islocated in another PLMN or another country, then MME 130 mayauthenticate that a location request is allowed from this PLMN or fromthis country and may return an error response if it is not allowed. Ifthe PSL message includes indicators of privacy related action, then MME130 may determine a required privacy related action. If UE 110 is in anidle state, then MME 130 may perform a network triggered service requestprocedure in order to establish a signaling connection for UE 110 and toassign a specific eNB (e.g., eNB 120) to UE 110 (step 3). If the PSLmessage indicates that UE 110 should either be notified or be notifiedwith privacy verification, then MME 130 may notify UE 110 of thelocation request and may verify its privacy preference (step 4). Step 4may include sending a Location Notification Invoke message to UE 110. UE110 may wait for the user to grant or withhold permission and may thenreturn a Location Notification Return Result message to MME 130.

MME 130 may select E-SMLC 140 and may send a Location Request message toE-SMLC 140 (step 5). The Location Request message may include the typeof location information being requested, the requested LCS QoS, theidentity of the serving eNB, the UE positioning capabilities, etc. Ifthe requested location information and location accuracy within the LCSQoS can be satisfied based on parameters (e.g., eNB identity) receivedfrom MME 130, then E-SMLC 140 may send a Location Response messageimmediately (not shown in FIG. 5). Otherwise, E-SMLC 140 may determineone or more positioning methods to use and may instigate a positioningprocedure for the positioning method(s) (step 6). E-SMLC 140 may receivemeasurements from the positioning procedure and may compute a locationestimate for UE 110 based on the measurements. If E-SMLC 140 fails toreceive measurements, then it may use the current eNB identity to obtainan approximate location estimate for UE 110. E-SMLC 140 may also receivea location estimate from UE 110, which may be obtained with a UE-basedpositioning method, and may verify consistency of this location estimatewith the current eNB location. If the location estimate does not satisfythe requested accuracy and sufficient response time still remains, thenE-SMLC 140 may instigate another positioning procedure using the same ordifferent positioning method. If a vertical location coordinate isrequested but E-SMLC 140 only obtains horizontal coordinates, thenE-SMLC 140 may return the horizontal coordinates.

After completing the positioning procedure in step 6, E-SMLC 140 maysend a Location Response message to MME 130 (step 7). The LocationResponse message may include a location estimate for UE 110 obtainedfrom the positioning procedure, an indication of whether the locationestimate satisfies the requested accuracy, the positioning method usedto obtain the location estimate, a failure cause if a location estimatecould not be obtained, etc.

MME 130 may then return the requested location information to GMLC 160(step 8). MME 130 may return an error response to GMLC 160 if (i)permission is not granted by the user or is not received from UE 110 forthe privacy verification in step 4 or (ii) a valid location estimate isnot obtained from E-SMLC 140 in step 7. MME 130 may also return the lastknown location of UE 110 if allowed and if a valid location estimate isnot obtained. MME 130 may record charging information. The common MT-LRprocedure in PS and CS domain may be performed to return the locationinformation to LCS client 170 (step 9).

Notification and privacy verification with UE 110 may be performed priorto sending the Location Request message to E-SMLC 140, as shown in FIG.5. Notification and privacy verification may also be performed at thesame time or after sending the Location Request message. In these cases,location procedure 510 in step 6 may be stopped by MME 130 or thelocation estimate obtained from the positioning procedure may bediscarded by MME 130 if the UE privacy actions lead to a rejection ofthe MT-LR procedure by UE 110 or the user.

FIG. 6 shows a design of a call flow 600 for a Mobile OriginatedLocation Request (MO-LR) procedure for the first network architectureshown in FIG. 1. UE 110 may send an MO-LR Request message inside an RRCUplink Information (UL Info) Transfer message to eNB 120 (step 1). eNB120 may forward the MO-LR Request message inside a NAS Transport messageto MME 130 (step 2). MME 130 may verify the UE subscription for theMO-LR request. MME 130 may then send a Location Request message toE-SMLC 140 (step 3). The Location Request message may include LCS QoSand/or other information. E-SMLC 140 may perform a positioning procedurewith UE 110 appropriate for the LCS QoS (step 4). E-SMLC 140 may thenreturn the resultant location information (e.g., a location estimate forUE 110) to MME 130 (step 5). MME 130 may return the location information(e.g., the location estimate) in an MO-LR Response message inside a NASTransport message to eNB 120 (step 6). eNB 120 may forward the locationinformation in the MO-LR Response message inside an RRC DownlinkInformation (DL Info) Transfer message to UE 110 (step 7).

For an MO-LR transfer to third party, which is not shown in FIG. 6, MME130 may forward the location information obtained in step 5 to a V-GMLC.The location information may then be forwarded to an LCS client via anH-GMLC for UE 110 and an R-GMLC.

FIG. 7 shows a design of a call flow 700 for an emergency call for anyof the network architectures described above. UE 110 may detect anemergency call invocation from the user and may attach to EPS, if it isnot already attached, and may obtain a suitable IP bearer for the userplane in Serving Gateway 180 and PDN Gateway 182 (step 1). An emergencyindication may be used for the attach or the bearer allocation to informMME 130 that an emergency call is in progress. If UE 110 does not detectthe emergency call (e.g., does not recognize the dialed emergencynumber), then a Proxy Call Server Control Function (P-CSCF) within IMSnetwork 184 may reject the initial request and may force UE 110 to firstobtain emergency IP access and perform an emergency registration, whichwould ensure that a new emergency bearer allocation would occur via MME130.

After completing the bearer setup in step 1, UE 110 may send a SessionInitiation Protocol (SIP) INVITE message for the emergency call to anEmergency CSCF (E-CSCF) in IMS network 184 (step 2). The E-CSCF may senda location and/or routing request to LRF 162, which may forward thisrequest to GMLC 160 (step 3).

As a consequence of UE 110 requesting emergency access or an emergencybearer from MME 130 in step 1, MME 130 may select E-SMLC 140 and maysend a Location Request message to E-SMLC 140 (step 4). E-SMLC 140 maydetermine one or more positioning methods to use and may instigate apositioning procedure for the positioning method(s). E-SMLC 140, MME130, eNB 120 and/or UE 110 may perform the positioning procedure toobtain location information for UE 110 (step 5). For example, anetwork-based positioning procedure such as enhanced cell identity(E-CID) or a positioning procedure described below may be used for step5. After completing the positioning procedure, E-SMLC 140 may send aLocation Response message with a location estimate for UE 110 to MME 130(step 6).

After step 6, or after step 1 if steps 4 to 6 are not performed, MME 130may send a Location Report message to GMLC 160, which may be designatedto support location for the emergency call (step 7). MME 130 may beprovisioned with the address of GMLC 160. The Location Report messagemay include the UE identity (e.g., the IMSI), the IP address of MME 130,the location estimate for the UE (if steps 4 to 6 are performed), etc.GMLC 160 may acknowledge the Location Report message (step 8). If steps4 to 6 are not performed, or if the location estimate from steps 4 to 6is not suitable, then GMLC 160 may obtain location information for UE110 using a location procedure applicable to the network architecture,e.g., location procedure 510 in FIG. 5 (step 9). GMLC 160 may thenreturn the location information to LRF 162, which may use the locationinformation to obtain routing information for PSAP 188. LRF 162 may thenreturn the location information, PSAP routing information, correlationinformation (e.g., an ESQK), and/or other information to the E-CSCFwithin IMS network 184 (step 10). The E-CSCF may route the emergencycall to PSAP 188 and may also forward the ESQK (if available) to PSAP188, which may be indicated by LRF 162 (step 11). The remainder of theemergency call establishment may occur between PSAP 188 and UE 110 andother network entities (step 12).

PSAP 188 may send a request for more accurate location of UE 110 to LRF162, which may be determined using the ESQK (step 13). LRF 162 mayforward the request to GMLC 160. GMLC 160 may obtain locationinformation for UE 110 using a positioning procedure applicable to thenetwork architecture (e.g., location procedure 510 in FIG. 5) and mayprovide the location information to LRF 162 (step 14). LRF 162 may thenreturn the location information to PSAP 188 (step 15).

FIG. 8 shows a design of a call flow 800 for a UE-assisted or UE-basedpositioning procedure, which may be used for step 6 in call flow 500 inFIG. 5, step 4 in call flow 600 in FIG. 6, step 5 in call flow 700 inFIG. 7, etc. This positioning procedure may be used by E-SMLC 140 tosupport UE-assisted positioning, UE-based positioning, and delivery ofassistance data. In general, one or more of these positioning servicesmay be performed for UE 110 in the same positioning procedure.

E-SMLC 140 may send a Positioning Request message to MME 130 (step 1).The Positioning Request message may be an LCS-AP message and may carry aDownlink Positioning message or an LPP protocol data unit (PDU), whichmay be part of LPP. The description below assumes the use of theDownlink Positioning message instead of the LPP PDU. The DownlinkPositioning message may request location information (e.g., specificmeasurements) from UE 110, provide assistance data, query for UEcapabilities, etc. MME 130 may forward the Downlink Positioning messagein a NAS Transport message to serving eNB 120 (step 2). The contents ofthe Downlink Positioning message may be transparent to both MME 130 andeNB 120. MME 130 may not retain state information for the PositioningRequest message and may treat the response in step 6 as a separatetransaction. eNB 120 may forward the Downlink Positioning message in anRRC Downlink Information Transfer message to UE 110 (step 3).

UE 110 may store assistance data (if any) provided in the DownlinkPositioning message and may perform any positioning measurements andlocation computation (if any) as requested by the Downlink Positioningmessage (step 4). UE 110 may then send an Uplink Positioning message (oran LLP PDU) in an RRC Uplink Information Transfer message to eNB 120(step 5). The Uplink Positioning message may include the requestedlocation information (e.g., information for measurements made by UE110), information for the UE capabilities, a request for additionalassistance data, etc. eNB 120 may forward the Uplink Positioning messagein a NAS Transport message to MME 130 (step 6). MME 130 may forward theUplink Positioning message in a Positioning Response message to E-SMLC140 (step 7). Steps 1 to 7 may be repeated to send new assistance data,to request additional location information, to request additional UEcapabilities, etc.

FIG. 9 shows a design of a call flow 900 for a network-assisted ornetwork-based positioning procedure, which may also be used for step 6in call flow 500 in FIG. 5, step 4 in call flow 600 in FIG. 6, step 5 incall flow 700 in FIG. 7, etc. This positioning procedure may be used byE-SMLC 140 to support network-assisted positioning and network-basedpositioning.

E-SMLC 140 may send a Positioning Request message carrying a NetworkPositioning Request message to MME 130 (step 1). The Network PositioningRequest message may be an LPPa message, and the Positioning Requestmessage may be an LCS-AP message. The Network Positioning Requestmessage may request location information for UE 110 from RAN 120, mayquery for RAN capabilities, may include parameters for RAN 120 definingthe type of measurement information required, etc. MME 130 may send aLocation Request message carrying the Network Positioning Requestmessage to serving eNB 120 for UE 110 (step 2). eNB 120 may obtainlocation information for UE 110, as requested in step 2 (step 3). eNB120 may then return a Location Response message carrying a NetworkPositioning Response message to MME 130 (step 4). The NetworkPositioning Response message may carry the requested locationinformation, Cell Global Identity (CGI), etc. MME 130 may return aPositioning Response message carrying the Network Positioning Responsemessage to E-SMLC 140 (step 5). The Positioning Response message mayinclude the requested location information, the CGI, and any requestedRAN capabilities. Steps 1 to 5 may be repeated to request additionallocation information and/or RAN capabilities. E-SMLC 140 may compute alocation estimate for UE 110 based on the measurements from eNB 120.

The control plane solution described herein may provide variousadvantages. First, the control plane solution may be compatible with thesolutions for other radio technologies such as GPRS, which may enablecontinuing location support for emergency calls handed off betweendifferent radio technologies such as GSM, UMTS and LTE. Second, thecontrol plane solution may support stateless location in eNB 120 andstateless positioning procedures in MME 130. Location information andlocation activity may be hidden from MME 130 and eNB 120 where possiblein order to reduce impact to the MME and eNB. Third, UE-based andUE-assisted positioning protocol similar to RRLP or RRC may besupported. Fourth, disruption in location due to intra-MME/inter-eNBhandover may be avoided by having MME 130 communicate with E-SMLC 140.Fifth, the control plane solution can support positioning methodssimilar to those used for GSM and UMTS, which may simplifyimplementation. Sixth, positioning is possible without requiring supportby or explicit involvement of the UE. The control plane solutiondescribed herein may also provide other advantages.

FIG. 10 shows a design of a process 1000 for supporting locationservices and positioning by an E-SMLC, which may also be referred to asa location server or by other names. The E-SMLC may receive a locationrequest from an MME (e.g., in step 5 in FIG. 5, step 3 in FIG. 6, orstep 4 in FIG. 7) (block 1012). The E-SMLC may perform a positioningprocedure with a UE in response to the location request (block 1014).The E-SMLC may send a location response to the MME after the positioningprocedure (block 1016).

In one design, the UE-assisted or UE-based positioning procedure shownin FIG. 8 may be performed for block 1014. In this design, the E-SMLCmay send a downlink positioning message to the MME for forwarding to theUE. The E-SMLC may thereafter receive an uplink positioning message sentby the UE and forwarded by the MME. The downlink positioning message mayrequest location information from the UE and may further includeassistance data for the UE, a request for UE capabilities, etc. Theuplink positioning message may include the requested locationinformation. The downlink positioning message may be for a firstprotocol (e.g., LPP, as described for FIGS. 4A and 8) and may beencapsulated in a positioning request message for a second protocol(e.g., LCS-AP, as also described for FIGS. 4A and 8) below the firstprotocol. The uplink positioning message may also be for the firstprotocol and may be encapsulated in a positioning response message forthe second protocol. The requested location information may comprisemeasurements, and the E-SMLC may compute a location estimate for the UEbased on the measurements. The E-SMLC may send the location estimate inthe location response to the MME. The messages may also be referred toby other names.

In another design, the network-based positioning procedure shown in FIG.9 may be performed for block 1014. In this design, the E-SMLC may send anetwork positioning request message to the MME for forwarding to an eNB.The E-SMLC may thereafter receive a network positioning response messagesent by the eNB and forwarded by the MME. The network positioningrequest message may request location information from the eNB, and thenetwork positioning response message may include the requested locationinformation. The network positioning request message may be for a firstprotocol (e.g., LPPa, as described for FIGS. 4B and 9) and may beencapsulated in a positioning request message for a second protocol(e.g., LCS-AP, as also described for FIGS. 4B and 9) below the firstprotocol. The network positioning response message may also be for thefirst protocol and may be encapsulated in a positioning response messagefor the second protocol. The messages may also be referred to by othernames.

FIG. 11 shows a design of a process 1100 for supporting locationservices and positioning by an MME, which may also be referred to byother names. The MME may receive a request for location information fora UE (block 1112). This request may be a provide subscriber locationmessage from a GMLC (e.g., step 2 in FIG. 5), an MO-LR Request message(e.g., step 2 in FIG. 6), a message sent during emergency attach oremergency bearer setup (e.g., step 1 in FIG. 7), a message from an LCSclient, etc. The MME may send a location request to an E-SMLC inresponse to receiving the request for location information (block 1114).The MME may then assist with a positioning procedure between the E-SMLCand the UE, which may be initiated by the E-SMLC in response to thelocation request from the MME (block 1116). The MME may receive alocation response sent by the E-SMLC after the positioning procedure(block 1118). The MME may send a response for the request for locationinformation (block 1120). This response may include a location estimatefor the UE and may be a provide subscriber location ack message sent tothe GMLC (e.g., step 8 in FIG. 5), an MO-LR Response message (e.g., step6 in FIG. 6), etc.

The MME may perform a network triggered service request procedure withthe UE to establish a signaling connection for the UE (e.g., step 3 inFIG. 5). The MME may also perform notification and privacy verificationwith the UE prior to sending the location request to the E-SMLC (e.g.,step 4 in FIG. 5).

In one design of block 1116, which is shown in FIG. 8, the MME mayreceive a downlink positioning message sent by the E-SMLC to requestlocation information from the UE. The MME may forward the downlinkpositioning message to the UE. The MME may thereafter receive an uplinkpositioning message sent by the UE to return the requested locationinformation to the E-SMLC. The MME may forward the uplink positioningmessage to the E-SMLC. The MME may maintain no state information for thedownlink positioning message. The downlink positioning message may beencapsulated in other messages at lower layer, e.g., in a positioningrequest message by the E-SMLC, in a NAS transport message by the MME,and in an RRC downlink info transfer message by an eNB. The uplinkpositioning message may also be encapsulated in other messages at lowerlayer, e.g., in an RRC uplink info transfer message by the UE, in a NAStransport message by the eNB, and in a positioning response message bythe MME.

In another design of block 1116, which is shown in FIG. 9, the MME mayreceive a network positioning request message sent by the E-SMLC torequest location information from an eNB. The MME may forward thenetwork positioning request message to the eNB. The MME may thereafterreceive a network positioning response message sent by the eNB to returnthe requested location information to the E-SMLC. The MME may forwardthe network positioning response message to the E-SMLC. The networkpositioning request message may be encapsulated in other messages atlower layer, e.g., in a positioning request message by the E-SMLC and ina location request message by the MME. The network positioning responsemessage may also be encapsulated in other messages, e.g., in a locationresponse message by the eNB and in a positioning response message by theMME.

FIG. 12 shows a design of a process 1200 for supporting locationservices and positioning by a UE, which may also be referred to by othernames. The UE may perform a positioning procedure with an E-SMLC, withthe positioning procedure being initiated by the E-SMLC in response to alocation request sent by an MME to the E-SMLC (block 1212). The locationrequest may be sent by the MME in response to a request for locationinformation for the UE sent by a GMLC, an LCS client, or the UE. The UEmay also send a message to originate an emergency call, and thepositioning procedure may be performed for the emergency call. The UEmay perform notification and privacy verification with the MME prior to,during, or after the positioning procedure (block 1214).

In one design of block 1212, which is shown in FIG. 8, the UE mayreceive a downlink positioning message sent by the E-SMLC and forwardedby the MME to the UE. The UE may send an uplink positioning messagetoward the E-SMLC and forwarded by the MME. The downlink positioningmessage may request location information from the UE, and the uplinkpositioning message may include the requested location information. Thedownlink and uplink positioning messages may be encapsulated in messagesat lower layer.

FIG. 13 shows a block diagram of a design of UE 110, eNB/RAN 120, MME130, and E-SMLC 140. For simplicity, FIG. 13 shows (i) one or morecontroller/processors 1310, memory 1312, and transmitter/receiver(TMTR/RCVR) 1314 for UE 110, (ii) controller/processor(s) 1320, memory1322, transmitter/receiver 1324, and communication (Comm) unit 1326 foreNB/RAN 120, (iii) controller/processor(s) 1330, memory 1332, andcommunication unit 1334 for MME 130, and (iv) controller/processor(s)1340, memory 1342, and communication unit 1344 for E-SMLC 140. Ingeneral, each entity may include any number of controllers, processors,memories, transceivers, communication units, etc.

On the downlink, eNB 120 may transmit traffic data, messages/signaling,and pilot to UEs within its coverage area. These various types of datamay be processed by processor(s) 1320 and conditioned by transmitter1324 to generate a downlink signal, which may be transmitted to the UEs.At UE 110, the downlink signals from eNB 120 may be received andconditioned by receiver 1314, and processed by processor(s) 1310 toobtain various types of information for location services, positioning,and/or other services. For example, processor(s) 1310 may decodemessages used for the call flows described above. Processor(s) 1310 mayalso perform or direct process 1100 in FIG. 11 and/or other processesfor the techniques described herein. Memories 1312 and 1322 may storeprogram codes and data for UE 110 and eNB 120, respectively.

On the uplink, UE 110 may transmit traffic data, messages/signaling, andpilot to eNB 120. These various types of data may be processed byprocessor(s) 1310 and conditioned by transmitter 1314 to generate anuplink signal, which may be transmitted to eNB 120. At eNB 120, theuplink signals from UE 110 and other UEs may be received and conditionedby receiver 1324 and further processed by processor(s) 1320 to obtainvarious types of information, e.g., data, messages/signaling, etc. eNB120 may communicate with other network entities via communication unit1326.

Within MME 130, processor(s) 1330 may perform processing to supportlocation services and positioning, memory 1332 may store program codesand data for MME 130, and communication unit 1334 may allow MME 130 tocommunicate with other entities. Processor(s) 1330 may performprocessing for MME 130 in the call flows described above. Processor(s)1330 may also perform or direct process 1100 in FIG. 11 and/or otherprocesses for the techniques described herein.

Within E-SMLC 140, processor(s) 1340 may perform processing to supportlocation services and positioning, memory 1342 may store program codesand data for E-SMLC 140, and communication unit 1344 may allow E-SMLC140 to communicate with other entities. Processor(s) 1340 may performprocessing for E-SMLC 140 in the call flows described above.Processor(s) 1340 may also perform or direct process 1000 in FIG. 10and/or other processes for the techniques described herein.

Those of skill in the art would understand that information and signalsmay be represented using any of a variety of different technologies andtechniques. For example, data, instructions, commands, information,signals, bits, symbols, and chips that may be referenced throughout theabove description may be represented by voltages, currents,electromagnetic waves, magnetic fields or particles, optical fields orparticles, or any combination thereof.

Those of skill would further appreciate that the various illustrativelogical blocks, modules, circuits, and algorithm steps described inconnection with the disclosure herein may be implemented as electronichardware, computer software, or combinations of both. To clearlyillustrate this interchangeability of hardware and software, variousillustrative components, blocks, modules, circuits, and steps have beendescribed above generally in terms of their functionality. Whether suchfunctionality is implemented as hardware or software depends upon theparticular application and design constraints imposed on the overallsystem. Skilled artisans may implement the described functionality invarying ways for each particular application, but such implementationdecisions should not be interpreted as causing a departure from thescope of the present disclosure.

The various illustrative logical blocks, modules, and circuits describedin connection with the disclosure herein may be implemented or performedwith a general-purpose processor, a digital signal processor (DSP), anapplication specific integrated circuit (ASIC), a field programmablegate array (FPGA) or other programmable logic device, discrete gate ortransistor logic, discrete hardware components, or any combinationthereof designed to perform the functions described herein. Ageneral-purpose processor may be a microprocessor, but in thealternative, the processor may be any conventional processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices, e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration.

The steps of a method or algorithm described in connection with thedisclosure herein may be embodied directly in hardware, in a softwaremodule executed by a processor, or in a combination of the two. Asoftware module may reside in RAM memory, flash memory, ROM memory,EPROM memory, EEPROM memory, registers, hard disk, a removable disk, aCD-ROM, or any other form of storage medium known in the art. Anexemplary storage medium is coupled to the processor such that theprocessor can read information from, and write information to, thestorage medium. In the alternative, the storage medium may be integralto the processor. The processor and the storage medium may reside in anASIC. The ASIC may reside in a user terminal. In the alternative, theprocessor and the storage medium may reside as discrete components in auser terminal.

In one or more exemplary designs, the functions described may beimplemented in hardware, software, firmware, or any combination thereof.If implemented in software, the functions may be stored on ortransmitted over as one or more instructions or code on acomputer-readable medium. Computer-readable media includes both computerstorage media and communication media including any medium thatfacilitates transfer of a computer program from one place to another. Astorage media may be any available media that can be accessed by ageneral purpose or special purpose computer. By way of example, and notlimitation, such computer-readable media can comprise RAM, ROM, EEPROM,CD-ROM or other optical disk storage, magnetic disk storage or othermagnetic storage devices, or any other medium that can be used to carryor store desired program code means in the form of instructions or datastructures and that can be accessed by a general-purpose orspecial-purpose computer, or a general-purpose or special-purposeprocessor. Also, any connection is properly termed a computer-readablemedium. For example, if the software is transmitted from a website,server, or other remote source using a coaxial cable, fiber optic cable,twisted pair, digital subscriber line (DSL), or wireless technologiessuch as infrared, radio, and microwave, then the coaxial cable, fiberoptic cable, twisted pair, DSL, or wireless technologies such asinfrared, radio, and microwave are included in the definition of medium.Disk and disc, as used herein, includes compact disc (CD), laser disc,optical disc, digital versatile disc (DVD), floppy disk and blu-ray discwhere disks usually reproduce data magnetically, while discs reproducedata optically with lasers. Combinations of the above should also beincluded within the scope of computer-readable media.

The previous description of the disclosure is provided to enable anyperson skilled in the art to make or use the disclosure. Variousmodifications to the disclosure will be readily apparent to thoseskilled in the art, and the generic principles defined herein may beapplied to other variations without departing from the scope of thedisclosure. Thus, the disclosure is not intended to be limited to theexamples and designs described herein but is to be accorded the widestscope consistent with the principles and novel features disclosedherein.

What is claimed is:
 1. A method of supporting location services andpositioning, comprising: receiving a location request from a MobilityManagement Entity (MME) at an Evolved Serving Mobile Location Center(E-SMLC); performing a positioning procedure between the E-SMLC and auser equipment (UE) in response to the location request; and sending alocation response from the E-SMLC to the MME after the positioningprocedure.
 2. A method of supporting location services and positioning,comprising: sending a location request from a Mobility Management Entity(MME) to an Evolved Serving Mobile Location Center (E-SMLC); assistingwith a positioning procedure between the E-SMLC and a user equipment(UE), the positioning procedure being initiated by the E-SMLC inresponse to the location request from the MME; and receiving a locationresponse sent by the E-SMLC to the MME after the positioning procedure.3. An apparatus for supporting location services and positioning,comprising: means for performing a positioning procedure between a userequipment (UE) and an Evolved Serving Mobile Location Center (E-SMLC),the positioning procedure being initiated by the E-SMLC in response to alocation request sent by a Mobility Management Entity (MME) to theE-SMLC.